From: "H. Peter Anvin" <hpa@zytor.com>
To: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Avuton Olrich <avuton@gmail.com>,
LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>
Subject: Re: Fail to early boot with v2.6.27-rc2 to at least v2.6.29-rc2 due to dc1e35c
Date: Mon, 19 Jan 2009 14:24:46 -0800 [thread overview]
Message-ID: <4974FDAE.7080909@zytor.com> (raw)
In-Reply-To: <20090119221434.GF31356@linux-os.sc.intel.com>
Suresh Siddha wrote:
> On Mon, Jan 19, 2009 at 02:07:36PM -0800, H. Peter Anvin wrote:
>> Suresh Siddha wrote:
>>> Also, I wonder, if we should complain/scream during boot if we find only
>>> fewer cpuid levels on modern generation cpu's.
>>>
>> We should, or if this block is reversible, we should probably just undo
>> it (the reason people put this block in places is because of, ahem,
>> inferior operating systems having bugs.)
>>
>> Do you know how this is managed? Via an MSR?
>
> IA32_MISC_ENABLE MSR bit 22
LOL, the official name of this bit is "IA32_MISC_ENABLES.BOOT_NT4"; kind
of says it all. In fact, I remember the problems we had with NT4 and
CPUID back from the Transmeta days, and there, too, we ended up with a
CPUID hack which Linux unconditionally disables.
I'll write up a patch.
-hpa
next prev parent reply other threads:[~2009-01-19 22:25 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-19 14:04 Fail to early boot with v2.6.27-rc2 to at least v2.6.29-rc2 due to dc1e35c Avuton Olrich
2009-01-19 14:28 ` Avuton Olrich
2009-01-19 18:55 ` H. Peter Anvin
2009-01-19 19:31 ` Avuton Olrich
2009-01-19 20:07 ` H. Peter Anvin
2009-01-19 20:11 ` Suresh Siddha
2009-01-19 21:46 ` Avuton Olrich
2009-01-19 21:57 ` Suresh Siddha
2009-01-19 22:07 ` H. Peter Anvin
2009-01-19 22:14 ` Suresh Siddha
2009-01-19 22:24 ` H. Peter Anvin [this message]
2009-01-21 5:20 ` Andi Kleen
2009-01-22 22:22 ` Suresh Siddha
2009-01-22 22:40 ` H. Peter Anvin
2009-01-22 22:56 ` Suresh Siddha
2009-01-20 3:35 ` Valdis.Kletnieks
2009-01-20 6:36 ` H. Peter Anvin
2009-01-22 0:38 ` H. Peter Anvin
2009-01-22 2:26 ` Avuton Olrich
2009-01-22 8:28 ` Ingo Molnar
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